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Unveiling annealing texture formation and static recrystallization kinetics of hot-rolled Mg-Al-Zn-Mn-Ca alloy

Journal of Materials Science & Technology 2020年第8期36卷 104-118页

作者： Qinghang Wang Bin Jiang Aitao Tang Jie Fu Zhongtao Jiang Haoran Sheng Dingfei Zhang Guangsheng Huang Fusheng Pan State Key Laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing 400044China Chongqing Academy of Science and Technology Chongqing 401123China Research Institute for New Materials Technology Chongqing University of Arts and SciencesChongqing 402160China Shanghai Aerospace Equipment Manufactory Shanghai 200245China

The development of Mg-Al-Zn-Mn-Ca series alloys provides a potential prospect to achieve high strength and formability at room temperature(RT).The formation of elliptical annular texture is treated as a crucial factor for the enhanced RT formability.However,the origin of such an elliptical annular texture formation has been rarely reported.Herein,we unveiled the formation and evolution of elliptical annular texture in the hot-rolled Mg-1.6 Al-0.8 Zn-0.4 Mn-0.5 Ca(AZMX1100,wt.%)alloy after annealing at different temperatures for 1 h,and its static recrystallization(SRX)kinetics in given annealing temperature for different time.The results revealed that the formation of elliptical annular texture in the hot-rolled AZMX1100 alloy after annealing was derived from nucleation-oriented SRX mechanism,which took place in 200-300°C,induced by cracked chain-shaped Al2 Ca phases,contraction twins,intersections of double twins,intersections of double twins and grain boundaries and non-basal slips.On further annealing from300-450°C,the grains with 45°–70°transverse direction(TD)preferentially grew,which made elliptical annular texture extended along the TD.Based on the Johnson-Mehl-Avrami-Kolmogorov(JMAK)model,Avrami exponent n value was estimated to be 0.68–1.02,attributed to non-random SRX nucleation,giving rise to the lower activation energy QRof nucleation of^74.24 k J/mol.Since the co-segregation of Al,Zn and Ca atoms in grain boundaries created a strong interaction of solutes and grain boundaries,the hot-rolled AZMX1100 alloy exhibited the higher activation energy Qg(~115.48 k J/mol)of grain growth.

关键词： Mg-Al-Zn-Mn-Ca alloy Elliptical annular texture Nucleation Grain growth Static recrystallization kinetics

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Comparison of microstructures and mechanical properties of composite extruded AZ31 sheets

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Journal of Magnesium and Alloys 2019年第4期7卷 547-554页

作者： Yanfu Chai Yan Song Bin Jiang Jie Fu Zhongtao Jiang Qingshan Yang Haoran Sheng Guangsheng Huang Dingfei Zhang Fusheng Pan State Key Laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing 400044China Chongqing Academy of Science and Technology Chongqing 401123China Research Institute for New Materials Technology Chongqing University of Arts and SciencesChongqing 402160China Shanghai Aerospace Equipment Manufactory Shanghai 200245China

The microstructures and mechanical properties of the composite extruded AZ31/AZ31 and AZ31/4047 Al sheets were investigated and made a comparison to the conventional extruded AZ31 sheet.Owing to the introduced intense shear deformation at the interface during the composite extrusion,grain refinement and tilted texture were detected in AZ31 layers of the AZ31/AZ31 and AZ31/4047 Al sheets,while the conventional extruded AZ31 sheet exhibited a relative coarse,inhomogeneous microstructure and strong basal texture.The compressiontension yield ratio was increased gradually from the AZ31 to the AZ31/AZ31 and AZ31/4047 Al sheets.Besides,the AZ31/4047 Al sheet could successfully accomplish the whole bending forming process at room temperature,while the AZ31 and AZ31/AZ31 sheets were both bend-formed to failure with significant cracks in the outer tensile region under the identical bending parameters.Moreover,under the same bending strain,both the outward offset degree of strain neutral layer and the sheet thickening were more serious in the AZ31/4047 Al composite sheet than those of the AZ31 and AZ31/AZ31 sheets.The foremost reason was the quite wide gap of material properties between Mg alloy AZ31 layer(tensile loading in the outer region)and Al 4047 layer(compressive loading in the inner region).

关键词： Mg alloy sheet Composite extrusion Tension-compression yield asymmetry Bendability

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Influence of minor Ce additions on the microstructure and mechanical properties of Mg-1.0Sn-0.6Ca alloy

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Journal of Materials Science & Technology 2020年第2期37卷 26-37页

作者： Yanfu Chai Chao He Bin Jiang Jie Fu Zhongtao Jiang Qingshan Yang Haoran Sheng Guangsheng Huang Dingfei Zhang Fusheng Pan State Key Laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing400044China Chongqing Academy of Science and Technology Chongqing401123China Research Institute for New Materials Technology Chongqing University of Arts and SciencesChongqing402160China School of Metallurgy and Material Engineering Chongqing University of Science and TechnologyChongqing401331China Shanghai Aerospace Equipment Manufactory Shanghai200245China

The microstructure and mechanical properties of Mg-Sn-Ca-Ce alloys with different Ce contents(0.0,0.2,0.5,1.0 wt%)were studied at room temperature.Ce additions to ternary Mg-Sn-Ca alloy resulted in grain refinement as well as a change in the category of second phase from CaMgSn to(Ca,Ce)Mg Sn and Mg12Ce.The volume fraction of second phase increased with rising Ce content,which aggravated the restriction of DRXed grain growth during the extrusion process and eventually led to texture weakening of as-extruded Mg-Sn-Ca based alloys.In terms of plasticity,owing to vigorously activated basal slip and homogeneous distributed tensile strain in tension,the tensile ductility of as-extruded alloys reached the maximum value of 27.6%after adding 0.2 wt%Ce,which enhanced by about 26%than that of ternary MgSn-Ca alloy.However,further Ce additions(0.5 and 1.0 wt%)would coarsen the second phase particles and then impair ductility.The tension-compression yield asymmetry of as-extruded Mg-Sn-Ca ternary alloy was alleviated greatly via Ce additions,due to the joint effects of grain refinement,increased amount of strip distributed second phase particles and texture weakening.

关键词： Mg-Sn-Ca alloy Ce content Microstructure Texture Mechanical properties

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Intrinsic feature extraction using discriminant diffusion mapping analysis for automated tool wear evaluation

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Frontiers of Information Technology & Electronic Engineering 2018年第11期19卷 1352-1361页

作者： Yi-xiang HUANG Xiao LIU Cheng-liang LIU Yan-ming LI State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China shanghai aerospace equipment Manufacturer Shanghai 200245China

We present a method of discriminant diffusion maps analysis(DDMA) for evaluating tool wear during milling processes. As a dimensionality reduction technique, the DDMA method is used to fuse and reduce the original features extracted from both the time and frequency domains, by preserving the diffusion distances within the intrinsic feature space and coupling the features to a discriminant kernel to refine the information from the high-dimensional feature space. The proposed DDMA method consists of three main steps:(1) signal processing and feature extraction;(2) intrinsic dimensionality estimation;(3) feature fusion implementation through feature space mapping with diffusion distance preservation. DDMA has been applied to current signals measured from the spindle in a machine center during a milling experiment to evaluate the tool wear status. Compared with the popular principle component analysis method, DDMA can better preserve the useful intrinsic information related to tool wear status. Thus, two important aspects are highlighted in this study: the benefits of the significantly lower dimension of the intrinsic features that are sensitive to tool wear, and the convenient availability of current signals in most industrial machine centers.

关键词： Tool condition monitoring Manifold learning Dimensionality reduction Diffusion mapping analysis Intrinsic feature extraction

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Experimental Investigations of Axial Force Monitoring and Control for Friction Stir Welding Process

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Journal of Donghua University(English Edition) 2017年第4期34卷 498-502页

作者：王庆霞胡晓伟庞静珠尹玉环李蓓智 College of Mechanical Engineering Donghua UniversityShanghai 201620China shanghai aerospace equipment Manufacturer Shanghai 200245China

Friction stir welding( FSW) is a solid-state welding process that utilizes a rotating tool to induce gross material plastic deformation and join two parts together. A large number of studies have indicated that axial force control can be used to achieve good welding quality. However,in the welding process,due to workpiece's geometry error,improper clamping and other process variations,the axial force can vary significantly and produce welding defects.The control of force in the process of FSW is investigated. At first,the development and evaluation of a closed-loop control system is described,which is equipped with a custom real-time wireless force dynamometer for FSW. Then,an axial force controller is designed based on nonlinear force controllers for FSW. Experimental validations are carried out on an FSW platform. The experimental results demonstrate that the controller maintains the constant axial force and shows desirable dynamic behavior, even when the disturbance is encountered during the welding process.

关键词： friction stir welding(FSW) dynamitic force measure axial force control disturbance rejection

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Effect of Flexible Spine Motion on Energy Efficiency in Quadruped Running

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Journal of Bionic Engineering 2017年第4期14卷 716-725页

作者： Dongliang Chen Ningjie Li Hong Wang Lei Chen College of Mechanical and Electrical Engineering Harbin Engineering University Harbin 150001 China shanghai aerospace Electronic and Communication equipment Research Institute Shanghai 201109 China

Energy efficiency is important in the performance of quadruped robots and mammals. Flexible spine motion generally exists in quadruped mammals. This paper mainly explores the effect of flexible spinal motion on energy efficiency. Firstly, a planar simplified model of the quadruped robot with flexible spine motion is introduced and two simulation experiments are carried out. The results of simulation experiments demonstrate that both spine motion and spinal flexibility can indeed increase energy efficiency, and the curve of energy efficiency change along with spinal stiffness is acquired. So, in order to obtain higher energy efficiency, quadruped robots should have flexible spine motion. In a certain speed, there is an optimal spinal stiffness which can make energy efficiency to be the best. Secondly, a planar quadruped robot with flexible spine motion is designed and the conclusions drawn in the two simulation experiments are verified. Lastly, the third simulation experiment is carried out to explore the relationship between the optimal spinal stiffness, speed and total mass. The optimal spinal stiffness increases with both speed and total mass, which has important guiding significance for adjusting the spinal stiffness of quadruped robots to make them reach the best energy efficiency.

关键词： bionic quadruped robot flexible spine motion spinal stiffness energy efficiency locomotion experiment

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Metallographic structure,mechanical properties,and process parameter optimization of 5A06 joints formed by ultrasonic-assisted refill friction stir spot welding

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International Journal of Minerals,Metallurgy and Materials 2017年第2期24卷 164-170页

作者： Xin-bo Liu Feng-bin Qiao Li-jie Guo Xiong-er Qiu Hunan Provincial Key Laboratory of Grids Operation and Control on Multi-Power Sources Area Shaoyang UniversityShaoyang 422000China shanghai aerospace equipment Manufacturer Shanghai 200245China

Novel hybrid refill friction stir spot welding （RFSSW） assisted with ultrasonic oscillation was introduced to 5A06 aluminum alloy joints. The metallographic structure and mechanical properties of 5A06 aluminum alloy RFSSW joints formed without ultrasonic assistance and with lateral and longitudinal ultrasonic assistance were compared, and the ultrasonic-assisted RFSSW process parameters were opti- mized. The results show that compared with lateral ultrasonic oscillation, longitudinal ultrasonic oscillation strengthens the horizontal bond- ing ligament in the joint and has a stronger effect on the joint＇s shear strength. By contrast, lateral ultrasonic oscillation strengthens the ver- tical bonding ligament and is more effective in increasing the joint＇s tensile strength. The maximum shear strength of ultrasonic-assisted RFSSW 5A06 aluminum alloy joints is as high as 8761 N, and the maximum tensile strength is 3679 N when the joints are formed at a tool rotating speed of 2000 r/rain, a welding time of 3.5 s, a penetration depth of 0.2 mm, and an axial pressure of 11 kN.

关键词： aluminum alloys friction stir welding ultrasonic applications metallography mechanical properties parameter optimization

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Creep rupture behavior and microstructural evolution of modified 9Cr-1Mo heat-resistant steel

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Journal of Iron and Steel Research(International) 2018年第12期25卷 1303-1310页

作者： Fa-cai Ren He Wang Xiao-ying Tang Fei Chen shanghai Institute of Special equipment Inspection and Technical Research Shanghai 200062China Capital aerospace Machinery Corporation Limited Beijing 100076China National Engineering Research Centre of Die &Mold CAD Shanghai Jiao Tong UniversityShanghai 200030China

High-temperature creep rupture behavior of modified 9Cr-lMo steel used for steam cooler was investigated at temperature of 838 and 923 K and stress ranging from 100 to 250 MPa.Based on the analysis of creep rate-time curves,it is found that the creep rupture life decreases with the increase in the applied stress and temperature.The creep damage tolerance factor has been identified as a value of 8.In the normalized and tempered condition,the studied steel shows typical martensitic microstructure with Cr-rich M23C6 and Nb-or V-rich MX precipitates.Moreover,the Laves phase has been found along the grain boundaries.The fracture morphology characterized by field emission scanning electron microscope is adopted to reveal the creep failure mechanisms.The investigated results indicate the occurrence of the transgranular fracture under all the creep test conditions.

关键词： Creep rupture behavior Modified 9Cr-1Mo steel Microstructural evolution Fractography

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Improved Spatial Registration Algorithm for Sensors on Multiple Mobile Platforms

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Journal of shanghai Jiaotong university(Science) 2022年第5期27卷 638-648页

作者：吕润妍彭娜吴怡蔡云泽 Department of Automation Key Laboratory of System Control and Information Processing of Ministry of EducationKey Laboratory of Marine Intelligent Equipment and System of Ministry of EducationShanghai Jiao Tong UniversityShanghai200240China shanghai aerospace Electronic Technology Institute Shanghai Academy of Spaceflight TechnologyShanghai201109China Alibaba(China)Co. Ltd.Hangzhou311121China

This paper focuses on the spatial registration algorithm under the earth-center earth-fixed(ECEF)coordinate system for multiple mobile platforms.The sensor measurement biases are discussed with the attitude information of the platform into consideration.First,the biased measurement model is constructed.Besides,the maximum likelihood registration(MLR)algorithm is discussed to simultaneously estimate the measurement biases and the target state.Finally,an improved online MLR(IMLR)algorithm is proposed through a sliding window of adaptive size.Simulation results demonstrate that the proposed IMLR algorithm effectively improves the realtime ability of the system and can approach similar estimation accuracy to the conventional MLR algorithm.

关键词： spatial registration 3D sensors improved online maximum likelihood registration(IMLR)

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Investigations on High-Speed Flash Boiling Atomization of Fuel Based on Numerical Simulations

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1427-1453页

作者： Wei Zhong Zhenfang Xin Lihua Wang Haiping Liu School of aerospace Engineering and Applied Mechanics Tongji UniversityShanghai200092China Beijing Mechanical equipment Research Institute Beijing100854China

Flash boiling atomization(FBA)is a promising approach for enhancing spray atomization,which can generate a fine and more evenly distributed spray by increasing the fuel injection temperature or reducing the ambient pressure.However,when the outlet speed of the nozzle exceeds 400 m/s,investigating high-speed flash boiling atomization(HFBA)becomes quite challenging.This difficulty arises fromthe involvement ofmany complex physical processes and the requirement for a very fine mesh in numerical simulations.In this study,an HFBA model for gasoline direct injection(GDI)is established.This model incorporates primary and secondary atomization,as well as vaporization and boilingmodels,to describe the development process of the flash boiling spray.Compared to lowspeed FBA,these physical processes significantly impact HFBA.In this model,the Eulerian description is utilized for modeling the gas,and the Lagrangian description is applied to model the droplets,which effectively captures the movement of the droplets and avoids excessive mesh in the Eulerian coordinates.Under various conditions,numerical solutions of the Sauter mean diameter(SMD)for GDI show good agreement with experimental data,validating the proposed model’s performance.Simulations based on this HFBA model investigate the influences of fuel injection temperature and ambient pressure on the atomization process.Numerical analyses of the velocity field,temperature field,vapor mass fraction distribution,particle size distribution,and spray penetration length under different superheat degrees reveal that high injection temperature or low ambient pressure significantly affects the formation of small and dispersed droplet distribution.This effect is conducive to the refinement of spray particles and enhances atomization.

关键词： High-speed flash boiling atomization numerical simulations Eulerian description Lagrangian description gasoline direct injection

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